A micro-electro-mechanical system (MEMS) tuning fork gyroscope can have bias mechanisms due to interaction between the proof masses and the sense electrodes. One form of bias is caused by sense bias asymmetry, which is an offset in sense bias voltage due to material properties. This asymmetry can cause a displacement of the two proof masses relative to each other which, in turn, causes drive comb disengagement, lift to drive, and finally bias. Another form of bias is charging of exposed glass which causes time varying bias.